Foraging activity and food preferences of odorous house ants (Tapinoma sessile (SAY)) were investigated in both the field and laboratory. Foraging activity was examined in the field from April to September 2001 by attracting T. sessile to feeding stations containing a 20% sucrose solution. Ant foraging activity was recorded over a twenty-four hour period along with ambient temperature to examine possible correlations with ant activity patterns. Results indicate that foraging activity may be influenced by both time and temperature. In April and May when temperatures dropped below approximately 10 C, little or no foraging activity was observed. However, in the summer when temperatures were generally higher, foraging activity was greater during relatively cooler times of the day and night. Under laboratory conditions, T. sessile was attracted to feeding stations and foraged throughout the day and night at a constant temperature of approximately 25 C. Evaluations of seasonal food preferences using carbohydrate, protein and lipid samples were also conducted throughout the spring and summer. Results indicated no seasonal shifts in food preference in foraging ants; T sessile consistently preferred sugar and protein rewards over lipids. Macronutrient choice assays were preformed on T. sessile to evaluate specific food preferences. Several different carbohydrates, proteins, lipids and salts were tested in both liquid and gel formulation. Results indicated significantly greater consumption of sucrose solution at a concentration of approximately 20% compared with other sugars tested (fructose, glucose, trehalose and maltose). In addition, strong feeding responses were observed to both casein hydrolysate and lactalbumin hydrolysate at a 5% concentration. The addition of NaCl to 15% sucrose gel samples also enhanced feeding responses. Lipids were generally ignored by T. sessile and in most cases decreased consumption of the sample. Various amino acids did not enhance feeding responses and were similar to water. / Master of Science

The odorous house ant, Tapinoma sessile, is a widespread, common pest in North American residential areas, yet the understanding of how viral pathogens shape its behavior, management, and interactions with other insects remains limited. Over the course of my thesis, I characterized four novel viruses in T. sessile using metatranscriptomic analysis, investigated their infectivity, and explored how colony social organization influences viral infection patterns. Inoculation experiments confirmed active infection in T. sessile colonies, suggesting trophallaxis as a route for horizontal transmission. These viruses were prevalent in urban populations with polygyne, unicolonial traits, indicating a potential association between colony social structure, colony location, and virus presence and diversity. Additionally, common honey bee viruses including Deformed Wing Virus and Kashmir Bee Virus were detected in T. sessile colonies, with higher prevalence near beehives, indicating a route for virus spillover between the species. Furthermore, the impact of viral infection on foraging behavior was assessed, revealing altered activity and diet preferences in infected colonies and highlighting the need for modified control strategies. Finally, I explored virus transmission between T. sessile and associated arthropods and found shared viruses and active replication in arthropods within ant nests, indicating a novel case of virus spillover between ants and myrmecophiles. These findings offer insights into viral pathogen interactions within ant colonies, the influence of social organization on infection dynamics, and the potential for pathogen transmission between ants and associated arthropods and offer a deeper understanding of an important native ant species that may shape future pest management strategies. / Master of Science in Life Sciences / In my thesis research I studied the odorous house ant or sugar ant, a common pest in homes and businesses in North America, to understand how viral pathogens shape its behavior, management, and interactions with other insects. I discovered four new odorous house ant viruses infecting these ants using molecular analysis techniques and found that they can pass from ant to ant when they share food. Interestingly, these viruses were more common in urban ant colonies with multiple queens, suggesting a link between the ants' social structure and the viruses they carry. Additionally, I found viruses typically seen in honey bees in these ant colonies, especially when those colonies were close to beehives, indicating that the odorous house ant can pick up viruses from honey bees. Furthermore, I studied how these viruses affect ant behavior and found that infected ant colonies change their activity and food preferences. Lastly, I investigated if these viruses are able to jump from ants to other insects and found evidence that insects living in their nests shared the same or similar virus infections. These findings provide important insights into how viruses spread among ant colonies and nearby insects, how their social structure affects transmission of viruses, and how viruses can move between different species of insects. Understanding these interactions is crucial for developing better ways to control ant pests and for gaining a deeper understanding of this important native ant species.

The odorous house ant (<i>Tapinoma sessile</i>) is an adaptive and widespread pest ant species found in North America. Despite the economic and ecological impact of pest ants, effective management still faces many challenges and control failures with liquid spray insecticides in urban and natural environments. In many insects such as bed bugs and cockroaches, chemical control measures have resulted in insecticide resistance. However, in contrast to non-social insects, insecticide resistance has never been documented in social insects. The current study had three main goals. The first objective was to examine regional variation in <i>T. sessile</i> insecticide susceptibility to three classes of insecticides commonly used in urban ant control. The second objective was to compare insecticide susceptibility in <i>T. sessile</i> colonies collected in natural vs. urban areas. The final objective was to determine if insecticide susceptibility varies in workers vs. queens. A total of 30 <i>T. sessile</i> colonies were collected within a 50-mile radius of Purdue University campus, Tippecanoe County, Indiana. Fifteen colonies were collected in natural areas and 15 in urban areas. Insecticide susceptibility of all 30 colonies was tested using residual exposure assays. Urban and natural colonies showed no significant differences in tests with lambda-cyhalothrin and fipronil. In tests with dinotefuran, urban colonies were significantly more tolerant relative to natural colonies. These results suggest that habitat type does not reliably predict susceptibility levels in individual populations. Queens were found to be significantly more tolerant relative to their worker counterparts across all three insecticides. Lower insecticide susceptibility in the queens may explain why <i>T. sessile</i> is such a persistent pest in urban environments. This 15 study’s results can in part provide a foundation for the development of more effective and efficient control methods for <i>T. sessile</i>.